The distributed video coding (DVC) is a new type of video coding scheme which is fundamentally different from conventional video coding schemes. The key feature of the DVC is separate encoding and joint decoding which is attractive in many cases when communications between encoders are prohibited. The DVC is based on Slepian and Wolfs and Wyner and Zivs information-theoretic results from the 1970s. This paper reviews the recent patents on practical distributed video coding schemes. The key components in a DVC system, such as Slepian-Wolf coding, quantization, spatial and temporal decorrelation, correlation noise modeling, encoder rate control, etc., are discussed. Some practical DVC systems are introduced as examples. This paper also points out future works on this issue.